Structural studies on κ-carrageenan derived oligosaccharides

Oligosaccharides were prepared through mild hydrochloric acid hydrolysis of K-carrageenan from Kappaphycus striation carrageenan. Three oligosaccharides were purified by strong-anion exchange high-performance chromatography. Their structure was elucidated using mass spectral and NMR data. Negative-ion electrospray ionization (ESI) mass spectra at different fragmentor voltages provided the molecular weight of the compounds and unraveled the fragmentation pattern of the K-carrageenan oligosaccharides, 2D NMR techniques. including H-1-H-1 COSY, H-1-H-1 TOCSY and C-13-H-1 HMQC. were performed to determine the structure of a trisulfated pentasaccharide. 1D NMR and ESIMS were used to determine the structures of a K-carrageenan-derived pentasaccharide. heptasaccharide. and an undecasaccharide. All the oligosaccharides characterized have a 4-O-sulfo-D-galactopyranose residue at both the reducing and nonreducing ends. (C) 2002 Elsevier Science Ltd. All rights reserved.